The invention concerns a fuel filter with a filter housing and with a filter insert, arranged exchangeably in the filter housing, with a prefilter element and with a main filter element which are arranged, positioned one behind the other, in the filter housing in the direction of the longitudinal axis. The invention concerns moreover a fuel filter insert.
DE 10 2008 048 228 A9 and U.S. Pat. No. 3,900,400 B each disclose a filter with a prefilter element and with a main filter element which are arranged concentrically to the longitudinal axis of the fuel filter or positioned one behind the other in axial direction. A further fuel filter with two filter elements that are positioned atop each other and are fluidically connected in series is disclosed in EP 0 852 158 A1.
WO 2006/070221 A1 discloses a further fuel filter with a prefilter element and a main filter element which are arranged concentric relative to the longitudinal axis of the fuel filter.
Similar fuel filters are disclosed in DE 20 2006 004 527 U1 and EP 1 485 605 B1.
The fuel filter inserts of fuel filters must be exchanged in certain intervals, in case they are not constructed as lifetime components. The known filters exhibit a complex configuration of their filter housing and enable only a cumbersome exchange of the filter insert. When exchanging the filter insert, a large quantity of contaminated fuel remains in the filter housing after its removal from the filter housing so that the filter insert exchange is made difficult. Moreover, an introduction of contaminated, i.e., unfiltered, fuel into the clean side of the filter housing may occur. This can cause impairment of or damage to an injection system or internal combustion engine connected to the filter.